The present invention relates generally to filtration systems for use in industrial applications, such as cleaning machine tool coolant containing contaminants and machining chips and returning clean coolant to the machine tools for reuse, although the invention has aspects applicable to other uses, for example, for pumping various fluids, such as paint, chemicals, and the like. The present invention particularly relates to pumps and to apparatus and methods for mounting pumps used in such filtration systems to return clean coolant from a tank to machine tools such that the pumps are readily and easily removed from and reinstalled into the filtration tank for general maintenance purposes and to remedy specific pump problems.
In machine tool operations, settlement tanks containing filters are widely used to separate machine tool chips and other contaminants, referred to as swarf, from coolant so that clean coolant may be returned to the machine tools for reuse. Generally, such tanks are set below elevation such that sluiceways, likewise located below elevation, convey the contaminated liquid and machining chips to the settlement tank. The chips settle to the bottom of the tank and a dragout conveyor system is employed to convey the chips and swarf from the tank for removal, conventionally up a ramp located at one end of the tank. Filters are employed in the tank to separate the smaller chips and other contaminants from the coolant. While there are many different types of filters and arrangements thereof used for this purpose, one well known and commercially successful system manufactured and sold by the assignee hereof, Henry Filters, Inc., uses one or more horizontally disposed filter drums located adjacent the bottom of the tank. A suction is provided to the interior of the filter drum to pull coolant through the filter element. Filter cake, comprised of small chips and other contaminants, is thus formed on the outside of the drum surface. The drum is periodically indexed to enable a doctor blade to shave off a portion of the accumulated filter cake, which drops to the bottom of the tank for removal by the dragout conveyor.
In the example of a filtration system discussed above, a clean coolant tank is also provided in the tank for receiving the clean coolant filtrate. Although many types of centrifugal pumps are used, such as horizontal split case, end suction, and self-priming types, one embodiment of such a filtration system uses one or more vertical turbine-type pumps. These pumps are disposed in the clean coolant tank for applying suction to the interior of the filter drum(s), as well as for supplying clean coolant to a header for return to the machine tools. More particularly, these vertical turbine pumps each typically comprise an elongated casing connected at its lower end with one or more impeller stage(s) for pumping clean coolant filtrate upwardly through the elongated casing. The impeller stages of each pump are driven by an electric motor mounted at the top of the casing above the liquid level in the tank. The motor drives the impellers by a central drive shaft which extends the length of the casing through multiple bearing assemblies supported by the casing. The lower end of the pump is received in a receptor ring located to enable the pump suction to connect through a suction chamber to the interior of the filter drum(s). The outlet for each vertical turbine pump is located above the coolant level of the filtration tank and above the tank itself and is connected to a header into which the clean coolant is discharged for return to the machine tools. Such arrangement is generally described and illustrated in assignee's U.S. Pat. No. 4,507,061, issued Mar. 26, 1985.
From time to time, one or more of these elongated vertical turbine pumps must be removed from the tank for maintenance, including cleaning and/or replacement of bearings and seals as needed, and thereafter reinstalled. This has required disconnection of mechanical piping connections, such as by unbolting, between the pump and header as well an electrical disconnection of the electric pump motor. As will be appreciated, this involves considerable labor and expense. It also involves imposing on the user of the system requirements which greatly add tot he cost of the installation. For example, in certain installations, each vertical turbine pump may have a height of 20 feet or more. To remove such pump from an operating position in a tank below working level, sufficient headroom above the filtration tank must be provided to accommodate the entire height of the pump. For example, to enable a vertical turbine pump having a length of 20 feet or more to be lifted substantially vertically from the filtration tank requires headroom above the tank of approximately a like extent. It will be appreciated that these pumps are quite heavy and require for their removal use of an overhead crane or other lifting mechanism. In many installations, there is just simply insufficient headroom or access space above the tank to enable ready and easy removal and reinstallation of the pump.
Moreover, to remove such vertical turbine pump from an installation and reinstall it, the services of at least three skilled tradesmen are required, a millwright, an electrician and a pipefitter. Particularly, to effect removal, the electric motor must be disconnected, the bolted connections between the pump discharge and header must be removed, and valves must be closed to isolate the suction and discharge sides of the pump. Thereafter, the elongated heavy vertical turbine pump must be lifted from the tank without damaging it or adjacent ancillary equipment. Additionally, these vertical turbine pumps are quite expensive to manufacture and are usually custom-built to meet individual application needs. They also require lubrication, which frequently necessitates use of costly automatic lubricators, and customarily have multiple bearings and other ancillary equipment necessary to support their elongated drive shafts. Further, the motors require cooling and lubrication and produce substantial noise. As will be appreciated, it is desirable to eliminate or minimize noise levels as well as to eliminate the requirement for lubrication because periodic greasing requires substantial labor and adherence to maintenance schedules. Automatic greasing equipment, as required in some installations, substantially increases the cost of such installation. Still further, the entire area above the tank is typically misty from the coolant and moist air, driven by the motor fan for cooling purposes, and such moist air inherently dirties the electric motors, thereby increasing the probability of their malfunction. Thus, there has been a need in the industry to provide pumps which may be readily and easily removed and reinstalled in filtration tanks of this type without the foregoing and other attendant problems.
In an effort to solve some of these installation and attendant problems of this type of pump, assignee hereof installed in a commercial installation a conventional end suction centrifugal submersible pump modified at its suction inlet to provide a positive suction connection through a receptor ring with the suction side of a filtration drum. The discharge was connected by vertical piping fixed to the submersible pump to a header located above the coolant tank. In this installation, it is necessary, when removing the pump, to concurrently remove the entirety of the vertical discharge pipe extending from the pump discharge to adjacent the header above the coolant tank. This requires the same type of piping disconnection as previously indicated with respect to vertical turbine-type pumps. While that installation has proven satisfactory and solved certain problems, others remain, for example, the need to disconnect the discharge piping from the header and the need for adequate headroom necessary to lift the submersible pump, including its discharge piping, from the coolant tank.
According to the present invention, there is provided novel and improved pumps and related mounting apparatus for use, for example, in the settlement tanks of industrial machine tool coolant filtration systems, as well as methods for the installation and removal of the pumps. As will be appreciated, such settlement tanks preferably include a dirty coolant tank compartment in which one or more filters and a dragout conveyor are disposed. A clean coolant tank compartment is also preferably provided in the tank to facilitate continuous pumping of clean coolant to the machine tools while the filter or portion thereof is cleaned as explained in detail hereinafter. Certain installations may, however, have only a dirty coolant tank compartment. More particularly, the present invention provides pumps for use preferably in the clean coolant tank compartment (although such pumps may likewise be used in the dirty coolant compartment) and which pumps may be readily and easily removed from and reinstalled in the coolant tank without draining the tank, disconnecting or reconnecting pipe couplings, joints and electrical connections, or manually closing valves, and without the need for substantial headroom or overhead access space. Moreover, the pumps hereof are disposed at the lowest point in the compartment to reduce the vertical lift of the coolant from the tank to the pump, and in certain embodiments hereof, to enable use of standard foot-mounted electrical motors rather than special vertical turbine motors, afford easy maintenance, minimize or eliminate the need for lubrication, eliminate numerous wear points and operating noise, minimize the number of bearings and areas for failure and minimize the number of skilled tradesmen involved in removing and installing the pumps.
In a preferred embodiment of the present invention, there is provided a pump having an axial inlet or suction port at its lower end adjacent the pump impeller stage or stages and a pump discharge head adjacent the upper end of the pump having an integral conduit defining a pump outlet port or ports. The pump discharge head includes a pair of axially spaced end walls defining a chamber for receiving coolant flowing upwardly from the impeller through these outlet ports. The clean coolant tank compartment has a false bottom defining an underlying chamber in communication with the suction side of the filter. A suction or inlet receptor is mounted on the false bottom for receiving the lower suction port of the pump and placing it in communication with filtered coolant on the suction side of the filter drum. Above the suction or inlet receptor, there is provided a housing or discharge receptor which receives the discharge head of the pump. The receptor is structurally supported by the tank.
More particularly, when the pump is in the operative position in the tank, its suction port is received in the suction receptor, placing it in communication with the suction side of the filter drum. The discharge receptor preferably comprises an annular ring which forms, with the end walls of the pump discharge head and the internal conduit, an annular chamber for receiving the pressurized coolant pumped upwardly by the impeller(s). An outlet conduit having a check valve is fixed in and to the tank at a location below the coolant level in the tank and communicates the pressurized coolant between the annular chamber and a header.
In this form of the present invention, the drive for the pump is provided by an electric motor mounted above the tank for movement between operative and out-of-the-way positions. The motor drive shaft is coupled to an elongated shaft which carries the pump. Preferably, an axial thrust bearing, for example, a Kingsbury bearing, supplied with coolant, is disposed adjacent the upper end of the pump discharge head such that the axial downward thrust caused by the pumping action is carried by the discharge receptor. Consequently, the drive shaft for the pump may simply carry torque loading rather than tension stresses. This permits use of a torque coupling only, such as a spline connection, rather than a coupling which transmits both torque and tension. The electric motor drive shaft is therefore readily removable from the drive shaft for the pump.
Typically, a plurality of pumps are provided the tank, the other pumps of the system being similarly constructed. In operation, the pumps draw filtrate, i.e., clean coolant, from the filter(s) through the lower axial suction ports of the pumps. The filtrate is pumped into the chambers defined between the end walls of the pump discharge heads and the discharge receptors for transmission through the outlet conduits past the check valves to the header.
To facilitate removal of a pump from the tank and its installation into the tank, the pump is provided with lateral guides which engage guideways carried by the tank. These guideways center the pump to ensure that the pump is properly aligned with the discharge and suction receptors.
When it is desired to remove the pump of this embodiment of the invention from the tank, the drive shaft of the electric motor, located above the tank, is disconnected from the pump shaft. The electric motor is then pivoted into an out-of-the-way position. The pump may then be lifted vertically from the tank by an overhead crane or other lifting mechanism without further piping disconnection. When the pump is lifted, the suction port is withdrawn vertically from its suction receptor and both the pump discharge head and impeller stages are withdrawn vertically through the discharge receptor for removal from the tank. The check valve in the outlet conduit automatically closes to prevent communication between pressurized coolant in the header and the coolant in the tank. In multiple pump installations, a check valve is also carried by the suction receptor to prevent loss of suction pressure on the filter by the other pump(s) when one pump is being removed. This latter check valve also automatically closes upon removal of the pump. The guides and guideways also maintain the pump centered during vertical movement to facilitate its removal.
When it is desired to install or reinstall the pump into the coolant tank, the pump is lowered to engage the pump guides with the tank guideways. The pump is thus centered with respect to the receptors. Upon further lowering movement of the pump, the lower end of the pump, including the impeller stages, is received through the discharge receptor and the suction inlet is subsequently slidably received in the suction receptor adjacent the bottom of the tank. As this occurs, the lower end wall of the pump discharge head is likewise received through the discharge receptor for sealing engagement on a radially inwardly extending abutment or flange formed along the inside lower end of the discharge receptor. The upper end wall of the discharge head also sealingly engages the upper end of the discharge receptor, thereby forming the sealed pump outlet chamber. Once the discharge head is seated in the discharge receptor, the electric motor is swung into operative position and its drive shaft is coupled with the pump drive shaft whereby operation of the pump may be resumed.
In another form of the invention, the pump and ancillary fittings within the tank are similar to those described previously in the first embodiment In this form, however, the electric motor and drive coupling therefor are replaced by an electric submersible pump motor secured directly on top of the discharge head of the pump.
When it is desired to remove the submersible pump of this embodiment, an overhead crane or other lifting mechanism is simply attached to the submersible motor and the latter is lifted vertically from the tank. When lifting, the lower suction port is disconnected from the suction side of the filter drum and the discharge head is removed from the discharge receptor, the check valve in the outlet conduit automatically closing. No electrical, piping or other mechanical disconnections are necessary to effect pump removal in this embodiment. For example, with a sufficiently long power cord, the pump may be removed and repaired essentially on site. Moreover, because of the substantially shortened height of the combined submersible electric drive motor and the pump due to the direct mounting of the electric motor to the discharge head, very little headroom or access space above the tank is required to remove the submersible pump of this embodiment from the tank.
In a further embodiment hereof, there is provided a combined suction/discharge receptor ring mounted on the false bottom of the clean coolant compartment. The ring has an opening in communication with the outlet conduit. In this form of the invention, the pump comprises a head having spaced end plates between which is mounted an impeller. The lower plate has an opening and the margins of the plates have seals for sealing against the suction/discharge receptor ring when the pump is mounted in the ring with the opening in the end plate in communication with the coolant compartment below the false bottom. Thus, the impeller affords a suction on the filter for flowing clean coolant from the suction side of the filter into the clean coolant compartment and into the pump head and through the opening into the outlet conduit for delivery to the header.
To install this motor/pump unit, the unit is lowered using suitable guides to center the plates for guided movement into the receptor ring. Consequently, both positive suction and discharge connections are afforded in response to the lowering movement of the motor/pump unit. To remove the unit, it is simply lifted from the receptor ring, thereby effecting disconnection on both the suction and discharge sides without the necessity for positively disconnecting pipes or couplings or electrical connections. Also, the check valve automatically closes to separate coolant in the clean compartment from pressurized fluid in the header. As in all embodiments of the invention, the height of the motor/pump unit in this embodiment is substantially reduced in comparison with the height of the vertical turbine-type pump discussed previously and, consequently, only minimal headroom or access space above the tank is necessary to remove and reinstall the pump.
In a still further embodiment of the present invention, there is provided a submersible pump having a lower axial end suction inlet extended for reception in he suction receptor, an impeller, a volute passage having a lateral discharge outlet and a submersible electric motor mounted above the impeller to drive the latter, whereby coolant may be pumped from the suction side of the filter through the end suction inlet through the pump and the lateral discharge outlet. As in the first two embodiments described above, a suction receptor is provided adjacent the tank bottom. In this form, however, a movable coupling is provided between the lateral discharge outlet of the pump and a discharge conduit in communication with the header such that the lateral discharge outlet of the pump may be connected to, and disconnected from, the discharge conduit communicating with the header upon movement of the pump in a vertical direction. To accomplish this, a coupling is provided which is axially movable in a lateral direction into and out of sealing engagement with the pump discharge outlet when the pump is situate in otherwise operative position in the tank. For example, a flexible coupling may be used and displaced axially under control of pneumatic or hydraulic cylinders. Alternatively, a mechanical control may be provided, for example, mechanical cams, to displace the coupling in an axial direction. Thus, upon lowering and guiding the submersible pump into the tank, the axial suction inlet of the pump is disposed in the suction receptor. The lateral discharge conduit is located by the guides opposite the movable coupling. The movable coupling may then be activated to move axially and seal against the lateral discharge outlet of the pump. This places the lateral discharge outlet of the pump in communication with the discharge conduit of the tank.
To remove the submersible pump of this embodiment from the tank, the lifting mechanism is simply attached to the pump. The pneumatic, hydraulic or mechanical drive means are actuated to withdraw the movable coupling from sealing engagement with the lateral discharge conduit. This frees the submersible pump from the discharge connection, it being appreciated that the check valve in the outlet conduit automatically closes as in the previously described embodiments. The pump may then be lifted vertically from the tank, thereby automatically breaking the suction connection.
Significantly, in all of the previously described embodiments of the present invention, the pump may be raised from the tank and lowered into the tank to make positive discharge and suction connections substantially simultaneously and without the need to make any bolted connections or disconnections. Importantly, the prior need for substantial headroom or access space above the tank in order to remove the pumps from the tank is minimized or eliminated. With this system, only a single tradesman is necessary to remove the pumps, thus eliminating substantial labor and expense. Other pumping equipment, for example, the multiple bearings in the elongated shaft of the previously utilized vertical turbine pumps, are entirely eliminated. Further advantages accrue to the foregoing described arrangements which use the submersible pumps in that no lubrication is required except to the extent that the coolant pumped affords lubrication. Noise levels are also virtually non-existent because of the submerged nature of the pumps.
Thus, in accordance with a preferred embodiment of the present invention, there is provided apparatus for pumping liquid comprising a tank for containing the liquid and having an outlet conduit, a pump for operative disposition in the tank below the liquid level therein and having an inlet port, a discharge head and an impeller mounted for rotation about an axis for supplying liquid from the tank through the inlet port to the discharge head. Means are carried by the pump head defining at least in part a chamber for receiving the liquid supplied to the head. Means are also provided cooperable between the tank and the pump for removably mounting the pump in the tank including a housing carried by the tank in communication with the tank outlet conduit, the housing defining in part the chamber when the pump is operatively disposed in the tank whereby liquid from the chamber may be discharged into the tank outlet conduit. Preferably, the housing includes an enclosure for encompassing at least in part the pump head when the pump is mounted in the tank, the pump head including a pair of axially spaced end walls defining the chamber therebetween, and means are carried by the end walls for engaging the enclosure such that the chamber is defined in part between the enclosure and the end walls and lies in communication with the outlet conduit and the inlet port.
In another aspect of the present invention, there is provided apparatus for pumping a fluid, comprising a pump having an inlet port, a head and an impeller mounted for rotation about an axis for pumping fluid through the inlet port to the head, means carried by the pump head defining at least in part a chamber for receiving the fluid supplied to the head, means for removably supporting the pump including a housing having an outlet conduit, and means cooperable between the housing and the pump for removably mounting the pump head in the housing with the housing defining the chamber when the pump head is mounted therein for communicating fluid from the pump head through the chamber into the housing outlet conduit.
In accordance with a further embodiment of the present invention, there is provided a liquid tank for containing a body of liquid having contaminants therein, a filter submerged in the tank for separating the contaminants from the liquid and providing a liquid filtrate, means for removing the separated contaminants from the tank, means for removing the filtrate from the tank including a liquid filtrate outlet conduit carried by the tank and a pump disposed in the tank below the liquid level therein and having an inlet port, a lateral discharge conduit and an impeller mounted for rotation about an axis for applying a suction to the filter and thereby supplying liquid filtrate from the filter through the inlet port to the discharge conduit, means cooperable between the tank and the pump for mounting the pump for movement in a vertical direction between an operative position submerged in the tank and an inoperative position removed from the tank, including a receptor carried by the tank and defining an opening in communication with the filtrate separated by the filter, a connecting element carried by the pump for slip-fit connection with the receptor in response to the vertical movement, a movable connecting member cooperable between the lateral discharge conduit and the filtrate outlet conduit and means for moving the connecting member to afford communication between the conduits when the pump is mounted in the operative position and to break communication between the conduits when the pump is moved from its operative position.
In another aspect of the present invention, there is provided in a tank containing a liquid, a filter having a suction side, communicating means in communication with the suction side of the filter, a filtrate outlet conduit below the liquid level in the tank, and a pump for disposition in the tank below the liquid level therein and having an inlet port, a discharge head and an impeller for suctioning liquid from the tank through the filter, the communicating means and the pump inlet port for discharge through the discharge head into the outlet conduit, a method of installing the pump in the tank below the liquid level thereof comprising the steps of lowering the pump into the tank to a location below the liquid level in the tank, positively effecting below the level of liquid in the tank a suction connection between said pump inlet port and the communicating means on the suction side of the filter and positively effecting below the level of liquid in the tank a discharge connection between the discharge head and the outlet conduit.
Accordingly, it is a primary object of the present invention to provide a novel and improved pump and apparatus for its installation and removal in an industrial filtration system, as well as a novel and improved method for installing and removing the pump whereby the pump may be readily an easily removed from and reinstalled in the filtration tank.
These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.